Typically, camshafts for internal combustion engines have been produced by casting or forging a blank of cast iron, steel or other metal which can be hardened by heating and quenching. After the blank has been formed, the lobes and bearing journals are rough and finish machined and then the lobes are hardened. After hardening, the lobes are ground to provide the desired contour and surface finish of the cam surface on each lobe.
The grinding of hardened lobes produces stresses detrimental to the useful life of the camshaft and sometimes produces burning and cracking of the lobes resulting in scrap and defective camshafts. Making camshafts this way has high material and labor costs, requires a large capital investment in production equipment and equipment to check every lobe of every camshaft for defects produced by grinding after hardening, and is relatively inefficient expensive and unsuited for high volume mass production.